1. Field of the Invention
Example embodiments of the present invention relate to an image forming apparatus, and more particularly, to an image forming apparatus with an improved drive system to reduce manufacturing cost.
2. Description of the Related Art
An image forming apparatus forms an image on a printing medium, and may be classified according to how an image is formed. Various ways of forming the image include an ink jet type method to form the image by discharging an ink, an electrophotographic type method to form the image by proceeding to charge, expose, develop, transfer, and clean to form the image, and a thermal transfer type method to form the image by using an ink ribbon.
The image forming apparatus includes an image forming unit (not shown) to form an image on the printing medium according to one of the above types of forming an image, and a discharging roller to discharge the printing medium having an image formed thereon by way of an image forming unit to the outside of the image forming apparatus. Also, for a double sided printing, that is, for printing on an opposite side of a single sided printed printing medium by passing it through the image forming unit again, some image forming apparatuses have a duplex printing path for transporting the single sided printed printing medium to the image forming unit again. Here, in case of the single sided printing, a discharging roller rotates in a clockwise or a forward direction to discharge the single sided printed printing medium to the outside of the image forming apparatus 100, whereas in case of the double sided printing, the discharging roller rotates in a counterclockwise or a reverse direction to reversely transport the single sided printed printing medium to the duplex printing path.
Also, a duplex roller is disposed on the duplex printing path to transport the printing medium reversely transported by way of the discharging roller to the image forming unit.
However, a typical image forming apparatus includes three driving motors to perform the printing operations, i.e., a first driving motor for driving a rotating body provided in the image forming unit, a second driving motor for driving the discharging roller, and a third driving motor for driving the duplex roller. Accordingly, a manufacturing cost a driving noise increase.
A solution to such problems from using a plurality of driving motors is suggested in co-assigned Korean Patent Publication No. 2006-24237 and No. 1999-20249. In Korean Patent Publication No. 2006-24237, a separate driving source for driving the image forming unit is necessary, so a decrease in a number of the driving source is limited. In Korean Patent Publication No. 1999-20249, a solenoid performing a piston movement is employed, so a driving configuration thereof is complicated, and it is difficult to make a small sized product due to a limitation on space that depends on the piston movement.